php文件下传不成功

    print_r($_FILES);
    $name=date("Ymd_his_").rand(100,999).".txt";     
    $path=dirname(__FILE__)."/upload/".$name;
     $result=move_uploaded_file($_FILES["file"]["tmp_name"],$path);
    echo $result;
    if(!$result)   echo $_FILES['file']['error']."
";
    else echo "上传成功";